The present invention relates to a liquid homogenous adjuvant blend for use with a herbicide. The present invention also relates to a method for dissolving dry ammonium sulfate in water to form a homogenous adjuvant blend with a non-ionic surfactant.
While herbicides perform a useful function in killing undesirable plants in a particular location, herbicide use poses problems in the areas of uniform application, safety and aesthetics. Specifically, herbicides frequently have limited solubility in water, are hazardous to individuals applying the herbicides and emit an unpleasant odor.
Glyphosate, N-(phosphonomethyl)-glycine, has use as a broad spectrum, post emergence herbicide. When glyphosate is applied to selected weeds, the glyphosate translocates within the weeds as the weeds grow and kills the weeds. Glyphosate is typically applied to the weeds in conjunction with an ammonium sulfate fertilizer at a concentration of about 8.5 to 17 lbs. glyphosate and fertilizer per 100 gallons of an aqueous spray mixture. The combined exposure of weeds to the fertilizer and glyphosate can substantially increase the efficacy of the glyphosate. The fertilizer accelerates the translocation of the glyphosate herbicide within the weeds, increasing the kill rate of the weeds. The use of an inexpensive fertilizer can increase the efficacy of the glyphosate at a minimum cost.
Ammonium sulfate is an inexpensive fertilizer. However, use of ammonium sulfate is problematic because ammonium sulfate solubility in water varies with variable water qualities throughout the United States. Water temperatures, hardness and mineral content all effect ease of mixing of ammonium sulfate into the spray mixture. This unpredictable solubility has been problematic for individuals applying glyphosate to kill weeds in a crop. The individuals typically prepare mixtures that include glyphosate using cold water under conditions, frequently out-of-doors, where insolubility problems cannot be satisfactorily resolved. The individuals then face the prospect of trying to apply a messy suspension of ammonium sulfate in water with the glyphosate. The suspension plugs conveying lines, causes an uneven application of the suspension on a crop of weeds resulting in an uneven kill rate in a field and directly exposes an individual preparing the solution to undesirable herbicide and fertilizer contact.
These problems have been exacerbated by conventional packaging of the ammonium sulfate and the non-ionic surfactant. Presently, the non-ionic surfactant and ammonium sulfate are packaged separately. Ammonium sulfate is sold in bags of various sizes and the surfactant is sold in containers holding about 2.5 gallons. This conventional packaging poses problems in container disposal, especially when all of the ammonium sulfate and non-ionic surfactant are not used.
In addition to a fertilizer, an aqueous glyphosate application typically includes an addition of a non-ionic surfactant of about 0.5 to 2.0% volume/volume (v/v) for increased spreading and penetration of a leaf of a weed. Attempts have also been made to include a surfactant with the ammonium sulfate and water in order to improve the solubility or at least dispersibility of the glyphosate and ammonium sulfate in water of a wide quality range. Unfortunately, commonly used surfactants, including non-ionic surfactants such as nonoxynol have not been successful in either solubilizing or dispersing efficacious concentrations of ammonium sulfate in an aqueous solution also including glyphosate.
The Moller U.S. Pat. No. 5,118,338 issued Jun. 2, 1992, describes a solid composition that includes glyphosate and a surface-active agent such as a nonionic polyglycol ether of a fatty alcohol. The free acid of glyphosate is in a solid particulate state. The surface active agent is applied to the surface of the glyphosate particles and dries to a solid state.
The Girardeau et al. U.S. Pat. No. 4,867,972, issued Sep. 19, 1989, describes a wettable powder having at least one active material such as a herbicide and at least one surface-active agent including a copolymer of an unsaturated carboxylic acid or a derivative of the carboxylic acid. This mixture also includes a surface-active agent having the formula: ##STR1## R.sub.b includes a compound with the formula: ##STR2## The composition also includes a surface-active agent that includes at least one mixed sulfate or phosphoric ester.